SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5164a7eec17ba2afab36635b4f484356b7add422e8516a0b03223c68ac0bae8' 
  AND token = 'U6THmuS3DTM03xAMH24swHobzdhjPiqnGusHuCS1nHo=' 
  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"
    }
  }
}