SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c15248c196e47bf1d336fa8f34b4d35a83b9533410c6a8b57cfffa81aec39a2c' 
  AND token = 'y6waAI7PiOdKJWDDo884QWpkCVmjVZ0h7viiQpx0sKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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