SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f657b5d14151ea4a804717562025bc40ac21410e1ee960f99b3de364857f397b' 
  AND token = 'wSOhscUwzD9eutx9nQV3rdzdGGf/qwR+pu/CzgwGfw8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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