SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '608021958290a475296e1163f37f781ca76812360f894b653f8fa5b4988536ba' 
  AND token = 'TN8EdHrtWvWMZCBZ4GyYR5zGAWvVMtK/aQjlGPLuuKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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