SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21888d7512027880e59c15a0fd97f2c44848558c5c01b78c59218199127ed31c' 
  AND token = 'kt9/pOXeiyFMnHm8Mkc3vUBkp5Upy3sIfWAQbGQpxrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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