SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77640fed9cb40271d3a8a5723c5d999753624bb59b3cefad793a762704afd71b' 
  AND token = 'r5ws82wwIAZi/jLQ6fTU0PJAFGIW/oDnfDgQyPkBUvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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