SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6540b52242fe6b971ede9016d74d56a5b8711761fac7c178ec28c520b1ff5d5' 
  AND token = 'gPJHWZ+VdjA01RF3jACJmawXezjG9/nKt1HnVqA1CUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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