SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2c1c6205fda06d039ce4963e0859d1f0733b3a388a45f1ae7170db9137ae3c6' 
  AND token = 'N7GnWqtVzHcZBzcY8pI5JjQnYvW2tMUp3Cj6nWUZ++k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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