SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f4be9426bcb387de2aec002094cd45b31a1de52d995765f7baf584eec0e7b6d' 
  AND token = '8kXTG5zlSKVKAO/TC8jYg10gbypLC1UlLoqV+Gg17rg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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