SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '65cf2e3fee113c90672cba6a69c58831fa9227748cf3403ebb3bd223846fc6c3' 
  AND token = 'sTBBMVw4nqMKLgYNEwdPR5pCJTv2ga7klQbErZm94NE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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