SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '38a856d72ce5d443db976064b699f5115a03c6d7a45b9026ba2c3d32d5d57731' 
  AND token = 'dscX/EhjptZDnoN7+IGoNc/kXPJn+7HhHd9+i/qbTM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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