SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8428c76947d1d2fd2996c937163fc334c7dbe1ebcd71f2c553a5f613bb52802d' 
  AND token = 'dj46empje+uOSCOszDiGXFTnQmEQ8AipTmw2lvwBwcE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}