SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5f6427d4166ccc75639139086a7103619f7975d65abaf01b15e55dc360ff1b6' 
  AND token = 'dfIet6SjGMrtSVtsK1IriUiEbySt0/S530ey1n5dBRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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