SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '194b1e3d1a78475764263ecac071564434a5a1229246309a4b450b1209f940d0' 
  AND token = 'O9HIc1STDo0xQ35cFmtFUv4QmZqrAKbp8BTltoW9vE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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