SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c5f5941cc02cbc202bd08ab0b2a90d39085e139c5db92d11c9841d1e4b93645' 
  AND token = 'XpEt4FdZ5jLkOS719sIHrYCxCEFFlXsvws4smxdjnjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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