SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35b362bd96d7f54fab39dd31dac5516c02664f50f4ec83900bcef24363774e81' 
  AND token = 'Rzc8or7kmiGmwePNsuECLJRlefv4lex9VP1bzse815E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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