SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adb58dd885e461829d6b59145e530f77f807f0e9d1d5c8dff287a93c940bd361' 
  AND token = '/CXg3uvsPeYe0itwPrHokjwlKWlEVQ1nWOdHxAB2mps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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