SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8f0bced8a42cce9508c62c1b575a1e942e002bdf52f15f1f012eb2d1d255a52' 
  AND token = 'dzLX9FKaFlGRqEwKZeTUOkmfzpMhxqcd+x+H5+CHgec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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