SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '243078cad0fe70b5dfb8ee78778698c13db009e96f900a09dc7de2a43499dc10' 
  AND token = 'rqjvEDeELJbwq2dkQcW0ugN3ruVykjPzHtyqRYUJhsQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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