SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c99febf7455f014d475ba14207475b57e947e5d10dac3a0c6f04627e275ef84e' 
  AND token = 'DsLARHsvHs7dDuQn8PeaJuOx/UEZVzdYAJOARMgo1c4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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