SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f8b9bff3b5aadaac60999a641e796389fcadb358f188e31b6b4f82af0df5bc7' 
  AND token = 'yI75vr2crS5SK+aWWqC5R9xqcGle/3TxjL1wYqt9Uog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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