SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f3511e28e415c402446834364bdbb216f818013480283abf4375fbd154576bd' 
  AND token = 'SzmlMifVWnwRIXtNGybm6EadVCEp2I6Op+CPNBNp0q4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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