SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6775b9e258645b587fcf0f0df387a0a668b34a6aa2ebca181b34b293955c4a61' 
  AND token = 'YnFmyn27FG/BFB8BCXubIBn1dF/xduQCzcDKYJJLcDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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