SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'd5befb5615b243f10aeb36fd31c03b88b0b07ffde41003c90f68700af3b14bf9' 
  AND token = 'fz0/gDm5wABv0vkxKPcxi0fyRnH5lklkufEk7FurZ4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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