SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98399f3550fabf75dad2fa04bd4bb4fec719d674cb18c4283044268e2a2e57ac' 
  AND token = 'iof4Du1eJvK2dDnH1/k7779qYgrGddrKetMEz5DONBk=' 
  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"
    }
  }
}