SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6736105f95cf8428b1efc7809479b3fb3f051060718cbea53b899ac45ebf1d2' 
  AND token = '6NVE3XtEVvkYrPHAS6N7oHJI8qjrOTpPda6oOqdXRoo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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