SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aaaf3671e49c7a3351efcff99e9e6cf19145c5950af8f948994f653710523671' 
  AND token = 'Cgwha21u6wyi1D7RXu8qc6TaDn7BFttlmSR3EPFExOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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