SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50e2d6423f4fbaffdd6ab15081341ea289cc4489efd43929c70d60b655eb3a85' 
  AND token = 'QOjgA7hmAf2sajPvrsRDJH3q49mCAZlKD/rBg8r4Lcc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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