SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '778b291fe5625707900bd51fa8c5a9b276c3258af2a7d927aded14ecb7bb9495' 
  AND token = 'kgCkzXmCYjFphfy78Rr2uygUjH/HJtq3wUVb0vnMyWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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