SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6eb6ee54534283eecb77ef62033d701287255b604f68b964e3f96ac429447247' 
  AND token = 'aMcYGONNnTbRQdgn0wG23wdFCrdCwnsX/TIPwgegYCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}