SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '762eddfccfaac5618fa55047b0ff7fce3a84c29a62097138d1389093b2011e80' 
  AND token = '/XSCeo7KlTgkc7zzhaypAXMtIav+Dl4GfCYhNSX8qtk=' 
  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"
    }
  }
}