SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '51b2cc24d1ee6a815d0d6c460f756ae7ee1a8fbd646960679c10bec34794ebdf' 
  AND token = 'M18BzC/AMBCjbufr/2Q0PchhM0V2HyTYa4xORAxZjHw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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