SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a036a8f61ea8dd21ad825d3c7bbb2d75b7c6c08d4a27eadbe871b3dca6aa5856' 
  AND token = 'PJcwEbB/Icjxv1eyHyxDqQ6+mAy+Ydmaubh3SmcEd0k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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