SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9bffa60feeca062ff5a06878f8ee08bea2d27db8d8ce66e9cef92da65c918d6a' 
  AND token = 'r2cEDfJGD7VbVSLHNPxWLiAitOEMt5TLEp64yePWQS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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