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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a612f939ce8b43be04befaee98fec64e1ad028d1832c18aa0ee6e391ca4c0de' 
  AND token = 'ax5AK7EBbzYlr6LU2qoN3q4GbbFk4nW8ncU8vPd81Ko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE								Impossible WHERE noticed after reading const tables