SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73f56e9fcfa53d0951e4053476cf95d1fd96416ec9ffbe4879d3992a24dba360' 
  AND token = 'BEMbJlGJFE+Nv0tI4bEwco90hgqUnVbvxFQqVSb/vA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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