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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af8a57b9105f8fbe4dc47cf87ffdeba2dd0e5d31563b5bd1843efb733aec4fa0' 
  AND token = '4wfeKWhvEEW5fSuZOzflYqiuDICaYhH+JLTDWJtj+tI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

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