SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b232c88e7c30f09bee0425f5085b1365486ac4138fc3c54e035c21d21e51b479' 
  AND token = 'MNAxasEpCPpuCl1xEjprSiW4GZj8fzqTWCnDewMr4fU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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