SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f7b093c55c17b676f1921323b45ec945bb4c06657dbd5387618ef3a5656a743' 
  AND token = 'gHiONdrgjhYMFISxsPPgl5P0aD6OaHHttm+zN3Dh0s8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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