SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a73b9db6546985a572a87f70a7a404c5e73322b480789e895b628dcfcee0b2d1' 
  AND token = 'qwaVmETT+KCecLKhDG5bU3u29/TJj0Kwpo68YNjRLOM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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