SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7755c3b76119ec8cfe1ba664fecad7380afe80d123399e5cf2ff88007edd76d5' 
  AND token = 'JWW4qhAi/rn3+JjM7osMlW9b3iibL9uLvzTRF4asNno=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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