SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b8dfad3199602408bdc271ffe960c243bbdcbdadc3ab187fd2123d504c44515' 
  AND token = 'wYk8hNJ9Bcp1nieGhdoFMbdFgcR/274xsFJG7/akuvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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