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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '509e014bf4a4402c0d4074e7434d18ec266f84a21b4bdee7d048f3d84bc1b527' 
  AND token = 'MRy9OsaWwrx8Whkc+4ZNQtV7TflSgFHGStGEy2PGSRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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