SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b28cafd539925b4efcb83cbfc9ff37d9f2f3ceb419c07368556a2b2c9275d718' 
  AND token = 'EyNXFpZJRG/1YW6NYWLE1JNYSrT60BGh97C9kgiYlVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}