SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '0521ec21983de4722f26b980d3823720651a91e39a1dcfc3cff1ff5141d32e36' 
  AND token = 'yFNNMNK2jf2/cJL/jQpmFBwoYipaziDz2qEcDNxV3pY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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