SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dd59c1340c0c7987cffbd2db195f96a44d6699cb19adf64aae439819ee74033' 
  AND token = '88hmPtPqg6Zrz1NCJflvQeSqGF9olddQvlhF0eD57tA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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