SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92bf6616ea7b09cc6a36422e2ded599a321a11d9643729f085b25a7d1be92d15' 
  AND token = '1B+1d7Mzpmtfi4rIoMSwW79S7kBOU7ldUav+Gnwi/IQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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