SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35c833012d7c0062f39d74d0787cc1bc19d4263db59e46b802e197304577cda4' 
  AND token = 'IsxIJ8r+viiQIbBAGt4PK1WugYlmUY1MdCECJZzX7Kk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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