SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4640d3318b1d3c7c03f80398a583e17e95909d2f8da7e0713a64e5a028a67dc2' 
  AND token = 'K1Mz9HHLavgno/MEcizwo1NK9E3Usfq7Ypf4cVDBYCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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