SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5f58d8335d9eba6ce551da571f5ae0ed82df38d507202862274c94ada3db900' 
  AND token = 'metabWbQ2sjdAXTlMzm1Q5A+hxODoKcUIo7kwrNj/WA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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