SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '750e57b0475b875ec0535bf82fd95cba8c04f679e59766d5968f56f3bdcc07c1' 
  AND token = 'oHURSKWjiOWONBPdBmL0bQuE4QRnTgXaD7S0yWDt5zU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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