SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '316c5e1139928f12a5fadcafe53e1fbc7dfcde436ec1892732225af258a8cac4' 
  AND token = 'rNh1euPxHjKec3IPXBsaorSiMw9nsC9/o3dRvmmqcp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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