SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b346e1c6395ec859662ba2122719f0b7fbbe15fa1f74b16002e277d3881ae366' 
  AND token = 'aapatJjRk3BnzJsmCnwlEUengb1WD2nGEaazXxpIpPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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