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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f9bdcda727f8a6703976bdce98f734d30a32cb0a96c1655454d939afa9dee4c' 
  AND token = '2Himw9adVj6JrQ3c0BhbEAZ+yu/Cs0rIWFcMnCBg1KI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}