SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4b691c04dffa67d7b73a1fbc9a49580ec52eed7e4723f8ad754e6fb2c5381d5' 
  AND token = 'uDbaQUcmqym375CQzmKw3HOjDpYwFdYDD5CF8lwQtdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

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