SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'abf31ad38f88fdeeab7682f42d3483caa711704bd7fa557dce61a3efafbebc78' 
  AND token = 'SMG2TbAN5Uk9MaNjJF/ujdWwjSPTkBjpQHkG+n5+ejI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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