SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83d52bf166cea94698572e51a2bc465f9c258fd51fb9771dac5dba0e90b9d3bf' 
  AND token = '+zN1++tPfbFVkEMhrnqzM0w/zp+55wf4q6XJa5TjY6o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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