SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fc7ce0251eee898dbe6301c1741e99a5c29d5021b8c088588357584d39ce8e0' 
  AND token = 'iZ3rNBYLEgkmDgK+UFc2LFlTgx7LcPGkSBYUoWl+cY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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