SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aeda35a1e724b0b0601f46523de2924c6d9794b97e2ef1bfb6e909577899991b' 
  AND token = 'Lj6QgEqSn9vTRmoM/aDy17+4Q1JdFtRrPMt9pnpNyhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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