SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c356be59a3f6a64139484e6f1d27338728b0fbbea7841173a86025f4ef0a1775' 
  AND token = 'M5YeQXmvzeYvzvUlFyIGhOgyDP3xwe/hCiSVxCTtkBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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