SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '820377c3eda584de3623e6bd100a06ae845c04f993dded4f4bd55a2ae4758e1e' 
  AND token = 'XRRvDMwms77rG4y9ZQuAQ1iUmf29aFtTJG8FicBpGAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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