SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '755826215e8c8a454d5924306f8227f31932eb4e5ef970abad78d6a98504a572' 
  AND token = 'nZzMnMztFQN5ji+e8eU4qle7cEI5/Dc5II18xddWNEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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