SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39a0a906e872675107ffca410e4300cf945928d3d920c30d72dab63085b6b737' 
  AND token = '18O9YFsY89KPp+Jj9ImRVWXzyq1aGZCdM3UKlfgH/hg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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