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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '750a0abb3006d3f57e7c8b6b73a7b9c4894115e3f2bb84ab8dd5e45bbef628a6' 
  AND token = 'cg3oQXAWoRDLpOPjy2urTEd7csFCK40Cbs3n5WMzjxU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

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