SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6be881fad795a0aef9d00d3fb638177301c142322664a5ea2b62790cb989d8df' 
  AND token = 'b7i7mQzq6P4t77TgCrnRULDXcIyAq53csZ3Rq5RLpnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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