SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b3e089261368ca3e4b82e198cc8e6f0510336b7be0a7a6d4aa00a2a66d9c7f3' 
  AND token = 'FEqpSWpRYxRZkgrhcu6jYojS1t0ezVC4kkxXaQpIPy0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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