SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af0fbe272bd78e2bf5db6751a9dbf2373abc84d7f611cb7eb547a502340e1451' 
  AND token = 'FfNmqMAqr7tBixKSYYWjiLemoSFWx+iEDe/SiSDwAJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}