SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18e9e76d7cc7ce9b1a11f4908f9c2d2e218b11b57b93f0a587728d3d8a302cda' 
  AND token = '0vDZ9fQGjY8HZHkhwqlY1/Qj9DUKXZ9U2sBjaqOlVik=' 
  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"
    }
  }
}