SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8a145bf81add0ec70970d2044cb34017785e48a5c36aca68c00e53c786ad837' 
  AND token = 'RrkrNM2aDkLE+jtDdfDtitgpngId2gLEbrD/TXe3Mdg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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