SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b2a8943daec25664ec903c6122f060e708b29581d2a8b60571991323013b0644' 
  AND token = 'NK8cs2o/t5jYRnMhz+lunBOn4BaLb/ZqL9I1DFafk3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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