SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6752079dadc105a94019695970ec270141ef7331ca30c92adb23f0a37f08fbd5' 
  AND token = '7PuyxMq1ERsbjMEnLiAKYJRT3hivyAc+4IfOXIZbEOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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