SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '579b50a4a1c324d7da5728384dd4bd94edb643f338c619169b52478f81b858f4' 
  AND token = 'mPR2i2K7qTetJqz7r+viAlXa41/WRuL3TF9RukcKxaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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