SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b40273c61be77d108aceaa752b409f78f31f71912109eb195f5224837ab865d' 
  AND token = 'UNsSQxPEmmKdeJXG4HD/sUsRF/OIyME2HcCnO9h4/NU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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