SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55da1a988beec02eedec30c3f49254b089ce26863d85389e2b0298dc3792c266' 
  AND token = '2rjPXu8wcCdpvdNzKOFYTcxfqBZ7M2ch+ilq2C/VHXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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