SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6ab51fba677db939c1a6d9b6eea64139374752c8512197bf792ddba073dd644' 
  AND token = '5nrcvmdsCQjHAdlzzNGvhPZzYCbhY1mGPg/ExcqtoNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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