SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c23b40ab45cd5a33391827fda2bde08606eaa2fd76b2a4bc9a2acefc8207e70' 
  AND token = 'efQeTiBCBLYBLTVQNxvam8rlnjRVRweVMLyFI5gtYh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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