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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42ccc4ad09dab18a0deb9c0b8be403788e810e40f65ca9c58e82949de8cedded' 
  AND token = 'Hqq4Ck64cJeBxcnZsbHOsMJk7HBny0izstZpfKuV7Yk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

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