SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '231f0461e7355f35a623adec4fffdae379c4b1531eb7a499ff9adea164dc88ef' 
  AND token = '/JPP9+ZyBuv25zvDwHb9tTa9ufhbiulpZvr5qqLyAWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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