SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4086aae3274da8a0b33b56ca996291eb857b521cb423a5f1e0c531e5fd9ca1f' 
  AND token = 'kRUv5cKLMI0g4k+MxIst0UUzhlX/r2gfEQMdcHq9vEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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