SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '188966b93b3b6fbfca5184ebd76dd83ab46d23ad402896738f68092cfb811b20' 
  AND token = 'jLYPDNkkp4Uu+cBNwFAqY6G3hk2WlfQKUm/xr+yOy50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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