SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3a531eae581fccc2d60fe0d894827b778b1359b02a0a857c4584c0137d94ba0' 
  AND token = 'RNdVemqwjNq+2NoHJuly7xj6ZiROUhO/oHjqJ9qasTE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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