SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7346728e10f402aaf577ce0957b0a3984759e08a320666200504a17a2873e68e' 
  AND token = 'x0f0QutdDlWUzwh7aRv0rImWIlTpPMfq2LG8LNkwM+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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