SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dc12e5dc542d51b8b85867a48a031975c598a89e012c912fde3d1d644ebeba1' 
  AND token = 'QTv/hItCPcE18juA8r1TbetlkQD+TTu+LtoRzvCHoOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}