SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '692b98753802978d9db02545fe616f5cd4876364a8919fe16a9d9d4746334b0a' 
  AND token = '1pSMBqLGVi797/hSXmos+5xTlzbSkunzBwCgzzToFVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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